April 29 (Reuters) - U.S. drugmaker Merck ( MRK ) said

on Tuesday it is investing $1 billion in a new Delaware plant to

expand domestic production as it prepares to deal with President

Donald Trump's tariffs.

The new facility will produce biologic drugs and Keytruda,

becoming Merck's ( MRK ) first in-house U.S. site to make the

blockbuster cancer treatment, the company said.

Merck ( MRK ) said last week its biggest tariff exposure is through

Keytruda and it has enough U.S. inventory for this year. It

estimated $200 million in additional costs for the levies

implemented to date.

The company expects labs at the new facility to be fully

operational by 2028 and produce experimental drugs by 2030.

The new plant would create at least 500 full-time jobs and

about 4,000 construction vacancies, the company said.

Merck ( MRK ) opened a $1 billion facility at its North Carolina

site last month to boost U.S. production.

The Trump administration has been putting pressure on U.S.

drugmakers to move their medicine production to the country and

announced probes into drug imports that set the stage for levies

in the sector.

U.S. drugmakers, including Eli Lilly ( LLY ) and Johnson &

Johnson ( JNJ ), have recently announced additional investments

to boost domestic production amid the tariff threat.